Preparation of organic phosphorus compounds from phosphorus, an alkyl halide, and anorgano-magnesium halide



United States Patent 3,099,690 PREPARATIGN OF ORGANIC PHOSPHURUS COMPOUNDS FROM PHUSPHQRUS, AN ALKYL HALHDE, AND AN ORGANO-MAG- NESIUM HALHDE Michael M. Rauhut, Norwalk, and Andrew M. Semsel, Stamford, Conn, assignors to American Cyanamid Cdmpany, stamford, Conn, a corporation of Maine No Drawing. Filed July 24, 1962, Ser. No. 212,124

3 Claims. (Cl. 260-6065) The present invention relates to organophosphorus compounds and to the preparation of same. More particularly, the instant discovery concerns secondary and tertiary aryl, alkyl and cycloalkyl phosphines, tetra-substituted phosphonium salts thereof, and tetralkylcyclotetraphosphines.

Pursuant to the present invention elemental phosphorus is brought into reactive contact, in the presence of an inert organic solvent, such as tetrahydrofuran, with an organomagnesium halide and an alkyl halide to produce the corresponding organophosphorus compounds.

According to a typical embodiment, White phosphorus is added to a solution of n-butylmagnesium 'bromide and butyl bromide in ether. The resulting mixture is refluxed for several hours and then tributylphosphine, tetrabutylphosphonium bromide and tetrabutylcyclotetraphosphine, for example, are recovered therefrom by distillation. As will be seen hereinafter, the addition of water to said resulting mixture after reaction of the phosphorus, organomagnesium halide and alkyl halide reactants results in the production of the secondary phosphines as well, viz., dibutylphosphine.

Typical organomagnesium halides within the purview of the instant discovery are monoand di-nuclear aryl magnesium halides, alkyl (C C magnesium halides and cycloalkyl magnesium halides, such as:

n-butylmagnesium bromide, n-butylmagnesium chloride, methylrnagnesium iodide, l-naphthylmagnesium iodide, 3-(trifiuoromethyl) phenylmagnesium chloride, 4-fluorophenylm'agnesium bromide, 4-methoxyphenylmagnesium chloride, octylmagnesium bromide,

heptylmagnesium bromide,

hexylmagnesium bromide, cyclohexylmagnesium chloride, n-dodecylm'agnesium chloride, heptafiuoropropylmagnesium bromide, 6-methoxy-2-naphthylmagnesium chloride, n-propylmagnesium chloride, 4-to1ylmagnesium bromide, 4-chlorophenylmagnesium iodide, and the like.

Obviously, from the above list of organometallic compounds, the organic moiety may or may not be substituted. Typical substituents for the organic moiety are those which under the conditions of the reaction contemplated herein are inert: halogen, such as fluorine, and the like, lower alkoxy, such as methoxy, ethoxy, propoxy and butoxy, and like substituents.

The elemental phosphorus reactant may be employed, as indicated hereinabove, as a finely-divided White phosphorus. However, elemental phosphorus in a diiferent physical state, such as molten phosphorus or phosphorus in the form of chunks, or other similar fractions, may be employed.

Typical alkyl halides within the purview of the instant discovery are those having from 1 to 12 carbon atoms in the alkyl moiety, such as the halides of: methyl-, ethyl-, propyl-, butyl-, penty1-, hexyl-, heptyl-, octyl-, nonyl-, decy1-, undecyl-, and dodecyl-. Typical halide moieties intended herein are chlorine, bromine, and iodine.

As pointed out above, the reactants are brought together in the presence of an inert organic solvent, i.e., a solvent which under the conditions of the reaction described herein does not react to any substantial degree with the reac-- tants. Typical inert solvents are others, such as the following: tetrahydrofuran (THF), diethylether, dibutylether, anisole, diethylether of diethyleneglycol, dioxane, and mixtures thereof.

In any given reaction of the type contemplated herein the reaction product mixture contains one or more of the organophosphorus compounds described hereinabove, viz., secondary organic phosphine, tertiary organic phosphine, tetra-substituted phosphonium salts thereof, or tetra-substituted-cyclotetraphosphine. The reaction equation is essentially as follows:

R=organic moiety of organomagnesium halide reactant R=organic moiety of organic halide reactant X :01, Br, I

Y=Cl, Br, I

m=0 or 1 n=1 or 2 Certain reaction conditions favor A or B or C. For example, the best yields of A are achieved operating at a temperature in the range of 20 C. to (3., although significant yields are realized at temperatures in the broader range of 0 C. to C. Generally a ratio of P:RMgX:RY of about 2:15:15 to about 2:4:4 is used. When Y is chloride, temperatures at the upper end of the broad range just given are generally used; when Y is iodide temperatures at the lower end of the range are best suited.

The reaction mixture, when Water is added thereto, as indicated above, yields the corresponding secondary phosphine, particularly when the reaction conditions just recited are employed.

In order to increase the yields of B in the above equation, temperatures on the order of 75 C. to C. are used, although temperatures as low as 50 C. and as high as 200 C. provide significant yields. Generally a reactant ratio PzRMgXzRY of at least 2:2:3, preferably at least 224:4, is employed. The addition of water to the reaction product mixture is optional, since it does not enter into the reaction but may be used to extract the phosphonium salt from the reaction product mixture.

In the case of product C, above, best yields thereof are achieved at temperatures in the range of 30 C. to 80 300 milliliters of tetrahydrofuran under nitrogen. The mixture is stirred at reflux (82 C.) for one hour. A white solid separates and the mixture becomes very thick. The reaction mixture is cooled to 25 C., diluted (3., although from C. to 150 C. may be employed. with 400 milliliters of ether, and treated dropwise with A ratio of P:RMgX:RY of about 221:1 is preferred. A 200 milliliters of water. The mixture is filtered from a ratio of at least 2:0.7:0.7 up to 2:425 is generally used, small amount of magnesium hydroxide, and the phases however, the yields diminishing porportionately the are separated. The aqueous phase is extracted with three farther away from the preferred ratio one gets. 50 milliliter portions of ether, and the combined organic 'It can be seen that the process of the present invention phases are dried over anhydrous sodium sulfate. Distilprovides a novel, straightforward and ready route to lation of the organic phase gives 9.0 grams of dibutylnumerous organophosphorus compounds. The products phosphine, a trace of tribntylphosphine, and 37.2 grams of Formulae A and C hereinabove have direct utility as of tetrabutyltetracyclophosphine. gasoline additives, since up to about 10 milliliters of any one of the phosphines, when dissolved in one gallon of E AMPLE H gasoline, aEOPdS Promctlon agalnst mlsfinng: Surface Reaction of White Phosphorus Butylmagnesium Bromide g l l -h d h d t f f 1 B b and Butyl Bromide -nteoter an,teproucso ormua ,aove, have direct utility as flame retardants on cotton cloth. a Stirred u lng (71 C.75 C.) mixture of 12.4 For example, a small but effective amount of a product glams gram atom) of white g P represented by B may be dissolved in a suitable solvent, grams mole) of butyl bromldej 100 mflhhter s such as isopropyl alcohol (heating ths alcohol enhances of tetrahydrofuran (THF) under a nitrogen atmosphere 1S solubility), cotton cloth dipped into the resulting solution added @PP mole of butylmagnelum bromlde and then dried. The phosphonium Salt acts as a flame 500 milliliters of tetrahydrofuran during 90 minutes. retardant on the cotton cloth Stirring at the reflux temperature is continued for 6 hours. The reactants of the Present invention may be brought The reaction mixture is cooledto room temperature and together in any sequence Good results are obtained by treated dropwise with 15 milliliters of water followed by establishing a solution of the organometallic reactant and 100 P FF of 48% N hydrobromlc Seven the alkyl halide in an inert organic Solvent and adding ty-five milliliters of ether is added and the aqueous phase the elemental phosphorus thereto 1S separated. The aqueous phase 1s evaporated to dry- Tha products are Separated and recovered by convem ness under reduced pressure (15 milliliters mercury), tional means, as will be seen hereinafter, such as by disand the risldue 1S ,extracfted Wlth chloroform' tillation, filtration, or the like, depending upon the soluchloroform 15 dned 9 anhydrous sPdmm bility of the Pwduct. carbonate and distilled to obtain 4.2 grams of dlbutyl- The present invention will best be understood from the phosphlne, 1.0 gram of tributylphosphme, and 6.1 grams following typical examples: of tetrabutylcyclotetraphosphme. The residue from the distributor consists of 13.8 grams of tetrabutylphosphon- EXAMPLE I ium bromide. Reaction of Buty] Magnesium Bromide h White Distillation of the dried organic phase from the reacphosphorus and ButylBmml-de 40 tion provides an additional 4.3 grams of dibutylphosphine. White phosphorus (31.0 grams, 1.0 gram atom) as cut into 0.3 gram pieces under Water and washed with acetone EXAMPLES LIL-XVIII and with benzene. The phosphorus is added in one por- The following examples in Table I are carried out tion to a solution of 0.55 mole of butylmagnesium broessentially as in Example II, above, excepting, of course, mide and 75.4 grams (0.55 mole) of butyl bromide in as shown in the table:

TABLE I Example P-l- RMgX RY Temp, Ratio, Organic Products No. C. lE zRMgXhRY solvent IIIB P n-gutylgiagnesium Butyl bromide 35 2:3:3 (0211910.- Dibutylphosphine,tributylphosphiue.

IOIH e. 1V3 P n-Bhtitylgagnesium Butyl chloride 2:3:3 THF Do.

0 011 6 V P Methylmag'nesiumiodide" Dodecyl iodide 2O 2:3:2 (0213920.. Methyldodecylphosphine,methyldidodecylphosphine, dimethyldodecylphosphine. VI P l-nephthyl-magnesium Methyl iodide 20 2:3:2 'IHF Methylbis-(l-nephthyl)-phosphine,

iodide. dimethyl-l-naphthylphosphine. VII P Plenylrgagnesium Isobutyl bromide..- 50 2:3:3 (C3H1)zO Phenylbislsobutylphosphi.ue.

Tom]. C. VIII P 3-(trifiuoromethy1)phenyl- Methyl iodide 213:4 'IHF Trimethyl-3-(trifluoro-methyl) magnesium chloride. phenylphosphonium iodide. IX P 4-fiuorophenyl magnesium Butyl bromide 2:424 (0311020.- Dibutylbis--fluorophenyyphosbromide. phonium bromide, tributy1-4- fluorophenylphosphouium bromide. X P Oyclohexylmagnesium Octyl bromide 80 2:2:6 THF Trioctylcyclohexyl-phosphonium chloride. bromide. XI P 4-chlorophenyl-magnesium Ethyl bromide 75 2:5:3 THF Bis-4-chlorophenyldiethyl-phosbromide. phonium bromide. XII P 4-methoxyphenyl-mag- Butyl bromide 70 2:3:5 THF Tributyl-4methoxyphenyl-phosnesium bromide. phonium bromide. XIII P n-Dodecylmagnesium n-Dodecyl bromide. 70 2:3:5 Tetra-n-dodecylphosphonium bromide. bromide. XIV P Heptafluoropropyl-mag- Butyl bromide 70 2:424 THF Heptafluoropropyltributyl-phosnesium bromide. phonium bromi e. XV P 6-methoxy1-2-naphthy1- Methyl iodide 70 224:4 THF G-methoxyQ-naphthyltrlmethylphosmagnesium chloride. phonium iodide. XVI P 4-tolylmagnesium chloride. .do 70 224:4 IHF 4-tolyltrimethylphosphonium iodide. XVIL--- P Mlethyliiagnesium Methyl bromide 70 2:1:2 'IHF -o Tetrarnethylcyclotetraphosphine.

IOml e. XVIII.-. P Octy1mag'nesiumbromide Octy] bromide 70 2:1:1 THF Tetraoctylcyclotetraphosphine.

1 Grain atom. 1 Mole.

3 Water is added to reaction mixture before recovering products.

Clearly, the instant discovery encompasses numerous modifications within the skill of the art. Consequently, while the present invention has been described in detail with respect to specific embodiments thereof, it is not intended that these details be construed as limitations upon the scope of the invention, except insofar as they appear in .the appended claims.

This application is a continuation-in-part of our copending application Serial No. 67,884, filed November 8, 1960, now abandoned.

We claim:

II. A method which comprises (a) bringing into reactive contact, in the presence of an inert organic solvent, elemental phosphorus, an alkyl halide and an organomagnesium halide selected from the group consisting of mono-nuclear aryl magnesium halide, di-nuclear aryl magnesium halide, substituted mono-nuclear iaryl magnesium halide, substituted di-nuclear taryl magnesium halide, alkyl magnesium halide, and cycloalkyl magnesium halide, said substituents for the monoand di-nucle'ar varyl magnesium moieties, al-kyl magnesium moieties and cycloalkyl magnesium moieties being selected from the group consisting of halogen and lower alkoxy, and said alkyl moieties of the 'organomagnesium halide reactants hereinabove having from 1 to 12 carbon atoms, and (b) recovering the resulting corresponding organophosphorus compound selected from the group consisting of tertiary arylalkyl phosphiue, tertiary alkyl phosphine, and tertiary cycloalkyl phosphine, tetra-substituted phosph'onium salts thereof, and tetralkylcycl-otetraphosphine.

2. The process of claim '1 wherein the reaction mixture is hydrolyzed before recovering the products and the corresponding secondary phosphine selected [from the group consisting of secondary aryl phosphine, secondary alkyl phosphine, and secondary cycloalkyl phosphine is formed.

3. The process of claim 1 wherein butyl magnesium bromide, white phosphorus and butyl bromide are reacted.

No references cited. 

1. A METHOD WHICH COMPRISES (A) BRINGING INTO REACTIVE CONTACT, IN THE PRESENCE OF AN INERT ORGANIC SOLVENT, ELEMENTAL PHOSPHORUS, AN ALKYL HALIDE AND AN ORGANOMANGNESIUM HALIDE SELECTED FROM THE GROUP CONSISTING OF MONO-NUCLEAR ARYL MAGNESIUM HALIDE, DI-NUCLEAR ARYL MAGNESIUM HALIDE, SUBSTITUTED MONO-NUCLEAR ARYL MAGNESIUM HAIDE, SUBSTITUTED DI-NUCLEAR ARYL MAGNESIUM HALIDE, ALKYL MAGNESIUM HALIDE, AND CYCLOALKYL MAGNESIUM HALIDE, SAID SUBSTITUENTS FOR THE MONO- AND DI-NUCLEAR ARYL MAGNESIUM MOIETIES, ALKYL MAGNESIUM MOIETIES AND CYCLOALKYL MAGNESIUM MOIETIES BEING SELECTED FROM THE GROUP CONSISTING OF HALOGEN AND LOWER ALKOXY, AND SAID ALKYL MOIETIES OF THE ORGANOMAGNESIUM HALIDE REACTANT HEREINABOVE HAVING FROM 1 TO 12 CARBON ATOMS, AND (B) RECOVERING THE RESULTING CORRESPONDING ORGANOPHOSPHORUS COMPOUND SELECTED FROM THE GROUP CONSITING OF TERTIARY ARYLALKYL PHOSPHINE, TETIRARY ALKYL PHOSPHINE, AND TERTIARY CYCLOALKYL PHOSPHINE, TETRA-SUBSTIUTED PHOSPHONIUM SALTS THEREOF, AND TETRALKYLCYCLOTETRAPHOSPHINE. 